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Impact of electronics over localized hot spots in multi-chip white LED light engines

Title	Impact of electronics over localized hot spots in multi-chip white LED light engines
Author	Muslu, Ahmet Mete, Arık, Mehmet
Publication Date:	2019
Publication Place	- IEEE
Subject	Junction temperature measurement, Forward voltage, White LEDs, Multi-chip LEDs, Optical measurements
Type	Document
Language	English
Digital	Yes
Manuscript	No
Library:	Özyeğin University
Library Asset ID	978-1-7281-2461-2
Record ID	82dba9e8-3f2e-4ea0-9933-f6099b5be4b3
Library Location	Mechanical Engineering
Date	2019
Notes	TÜBİTAK
Sample Text	In recent years, demand towards high power white LEDs has risen significantly covering a wide range of application areas. While many industries prefer more light extraction using less number of LED chips on their luminaires, the compact nature of the LED package poses some challenges for controlling junction temperatures of LEDs. Junction temperature measurement capabilities are limited to more simple measurements of board temperatures with added disadvantages of expensive measurement techniques. Although many studies focused on optothermal characterization of single LEDs, a few studies analyzed the junction temperatures of individual LEDs and their impacts on optical properties in multi-LED systems. Thus, this study introduces a new approach towards Forward Voltage Change Method and uses Integrating Sphere System to characterize thermal and optical traits of white multi-LED systems operating at different electrical conditions. Results show that additional electronic components in a multi-LED system can induce considerable thermal issues since it was determined that heat loads may reach up to total radiant power of LEDs and can decrease the conversion efficiency of a lighting unit by 6.1%. It was also shown that junction temperatures of LEDs can be affected by thermal conditions over the circuit and they need to be determined individually. Thus, a junction temperature measurement technique is introduced in this study for multi-chip LED systems enabling a high functionality in future studies for developing better cooling techniques and more lumen extraction.
DOI	10.1109/ITHERM.2019.8757383

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Özyeğin University

Impact of electronics over localized hot spots in multi-chip white LED light engines

Author Muslu, Ahmet Mete, Arık, Mehmet

Publication Date 2019

Publication Place - IEEE

Subject Junction temperature measurement, Forward voltage, White LEDs, Multi-chip LEDs, Optical measurements

Type Document

Language English

Digital Yes

Manuscript No

Library Özyeğin University

Library Asset ID 978-1-7281-2461-2

Record ID 82dba9e8-3f2e-4ea0-9933-f6099b5be4b3

Library Location Mechanical Engineering

Date 2019

Notes TÜBİTAK

Sample Text In recent years, demand towards high power white LEDs has risen significantly covering a wide range of application areas. While many industries prefer more light extraction using less number of LED chips on their luminaires, the compact nature of the LED package poses some challenges for controlling junction temperatures of LEDs. Junction temperature measurement capabilities are limited to more simple measurements of board temperatures with added disadvantages of expensive measurement techniques. Although many studies focused on optothermal characterization of single LEDs, a few studies analyzed the junction temperatures of individual LEDs and their impacts on optical properties in multi-LED systems. Thus, this study introduces a new approach towards Forward Voltage Change Method and uses Integrating Sphere System to characterize thermal and optical traits of white multi-LED systems operating at different electrical conditions. Results show that additional electronic components in a multi-LED system can induce considerable thermal issues since it was determined that heat loads may reach up to total radiant power of LEDs and can decrease the conversion efficiency of a lighting unit by 6.1%. It was also shown that junction temperatures of LEDs can be affected by thermal conditions over the circuit and they need to be determined individually. Thus, a junction temperature measurement technique is introduced in this study for multi-chip LED systems enabling a high functionality in future studies for developing better cooling techniques and more lumen extraction.

DOI 10.1109/ITHERM.2019.8757383